Fermentation Of Waste Research Articles

An innovative temperature control strategy to improve optically pure L-lactic acid production from food waste

Fermentation of food waste to lactic acid (LA) is a strategy for resource recovery. However, the poor yield and optical activity (OA) of L-lactic acid (L-LA) are major bottlenecks for such efforts. This study focuses on enhancing L-LA yield and optical purity from the food waste without sterilization and inoculation at pilot-scale. First, the effects of temperature on LA production were explored. A higher LA yield but lower purity was obtained under mesophilic conditions, whereas the opposite results were represented at high temperature. On the basis of these findings, a novel two-stage temperature regulation strategy was developed that combined the benefits of both temperature conditions. This strategy not only ensured a L-LA yield of 0.371 g/g volatile solid, but also achieved a high optical purity of 98.0%. The underlying mechanism is that high temperature could enrich L-lactic acid bacteria (LAB) and inhibit LAB producing both L- and D-LA. Overall, this innovative strategy may be well-suited for generating optically pure L-LA from food waste fermentation.

Recycling of animal protein wastes in the formulation of feed for Labeo rohita and Mystus vittatus—a comparative evaluation

Lactic acid bacteria (LAB) are key players in the fermentation of organic wastes and their recycling as feedstuff for fish. Whey, a common dairy byproduct in India, is a cheap source of LAB and can be used to ferment animal byproducts. An experimental study was designed to explore whether the whey fermented animal protein blend (WFAPB) could be used as a fishmeal replacer in the formulation of feed for both stomach-less carp fish Labeo rohita and stomach-bearing catfish Mystus vittatus. Experiments were performed with five isoproteinous, isolipidous, and isoenergetic feeds with WFAPB replacing fishmeal (FM) by 0% (T1), 25% (T2), 50% (T3), 75% (T4), and 100% (T5). Fifteen days of laboratory experiments with these experimental feeds revealed that more than 50% FM replacement level could result in excess postprandial absorption (6 h) of some essential and non-essential amino acids in the plasma of both fish. The postprandial absorption was more in M. vittatus than L. rohita. Ninety-day experiments were conducted in outdoor cement vats to measure growths and deposition of amino acids (AA) in muscle. Regression analysis was performed to find the optimal FM replacement based on four growth parameters and fifteen AA deposition in muscle. A two-phase fuzzy methodology was used to obtain Pareto-optimal replacement levels for each fish. The results demonstrated that FM replacement levels were 7.63% and 36.79% respectively for L. rohita and M. vittatus when only four growth parameters were considered. However, based on the FM replacement level that maximized deposition of 15 amino acids and growth parameters, it was found that 12.23% and 40.02% replacement of FM by the WFAPB was ideal respectively for L. rohita and M. vittatus. The results revealed that only a fraction of both essential and non-essential amino acids absorbed in plasma could be converted into protein and deposited as bound amino acids in the muscle. It is concluded that fermentation by whey is an inexpensive, easily available, and environmentally sustainable technique to recycle animal protein in the formulation of feed for fish, and the stomach-bearing carnivorous fish are more efficient in utilizing fermented animal protein blend than the stomach-less carps.

Study of Fruit Waste as Bio-battery Materials for Alternative Electricity

Organic vegetable and fruit waste may be used for green energy. Electrolyte-rich fruits can be used to make pollution-free bio-batteries. This study measures fermentation temperature and environment, pH before and after fermentation, electrical voltage, current, power, resistance, and energy in starfruit (Averrhoa carambola), mango (Mangifera indica), and strawberry (Fragaria) waste for 8, 10, and 12 days. A fully randomized factorial design was used for the experiment. The investigation concluded that 8-day strawberry waste fermentation was the optimum treatment. Temperature after fermentation was 28°C, ambient temperature was 29°C, pH before fermentation was 4, after fermentation was 3.2, voltage was 2.97 volts, current was 3.65 mA, power was 10.84 mW, resistance was 1,297 Ohm, and electrical energy was 73.32 mWh.

Role of Microbial Fermentation in the Bio-Production of Food Aroma Compounds from Vegetable Waste

Flavour is a key driver of consumer preferences and acceptability of foods, and the food industry has made food aroma compounds a crucial area of research. At present, about 80% of food aroma compounds are produced by chemical synthesis; however, alternative production approaches have been explored to meet consumers’ demand for “clean label” food products and “natural” aromas. Bio-production of food aroma compounds from vegetable wastes through fermentation has emerged as a promising alternative. This review showed that fungi and yeasts, and also lactic acid bacteria, can be used to produce aroma compounds through the fermentation of vegetable waste. The produced compounds were mostly responsible for sweet, fruity, and floral notes. Other molecules imparting cheesy/buttery, creamy, green, herbal, grass notes were also obtained through the fermentation of vegetable food waste. Substrates varied from agricultural waste such as rice bran to by-products and waste from the fruit supply chain, in particular pomace, peels, pods. During the study, challenges and limitations for the scale-up of the process emerged. The production of aromas is still strongly strain and waste dependent. Certain aspects thus still require attention to avoid that a joint occurrence of technical challenges may cause the failure of the process.

Nitrogen Metabolism during Anaerobic Fermentation of Actual Food Waste under Different pH Conditions

Acidogenic fermentation can convert food waste (FW) into small molecules of acids and alcohols, and the broth can be used as a carbon source of denitrification in wastewater treatment plants. However, the soluble nitrogen-containing substances generated in fermentation influence the quality of the carbon source, and microbial nitrogen transformation under different pH conditions has rarely been reported. In this study, four FW fermentation systems were operated continuously with a focus on nitrogen transformation, and metagenomic and metatranscriptomic analyses were used to reveal the metabolic pathways. The results showed that approximately 70% of nitrogen existed in solid organic matter, and the dissolution of solid proteins was limited at pH 4.0–5.0. The concentration of soluble nitrogen, encompassing both soluble organic nitrogen and ammonium, remained relatively stable across various pH conditions. However, high pH values promoted the conversion of soluble nitrogen-containing substances to ammonium, and its concentration increased by 122%, 180%, 202%, and 267% at pH 4.00, pH 4.27, pH 4.50, and pH 5.00. Lactobacillus played a crucial role in ammonium production via the arginine deiminase pathway at pH 4.0–4.5, and Prevotella was the key contributor with the assistance of glutamate dehydrogenase at pH 5.0. The findings provide insights into organic nitrogen transformation in acidogenic fermentation for optimizing FW treatment processes.

Influence of Inoculum Thermal Pretreatment Time on Hydrogen Production in Dark Fermentation

Dark fermentation (DF) of kitchen waste (KW) is a promising technology for the production of renewable biohydrogen. It can be both a method of obtaining clean energy and a sustainable waste management. Despite its potential, this process requires further research to improve efficiency. The aim of the research was to test the effect of thermal pretreatment of the inoculum on H2 and volatile fatty acids (VFAs) production in the DF process. The process was carried out at 37 °C, in batch mode. The digested sludge from the Group Wastewater Treatment Plant in Lodz was used as inoculum. KW from households was used as substrate. The inoculum was pre-treated at 70 °C for 15 and 30 min. Two control reference experiments were also used. The first without the inoculum, and the second without heating the inoculum. The thermal pretreatment inhibited methane production and increased hydrogen production. After the thermal pretreatment, the amount of CO2 produced during the process decreased compared to the bioreactor without inoculum pretreatment. Additionally, the main VFAs in the samples with pretreated inoculum were acetic and butyric acids, which are associated with hydrogen production in the biochemical pathways of the DF process. However, the time of thermal pretreatment had no significant effect on H2 production.

The Effect of Probiotic-Induced Fermentation of Restaurant Waste on the Growth of Common Carp (Cyprinus carpio) Fry

The study explores using the fermentation process to convert organic restaurant waste into fish feed, a promising solution for aquaculture. The aim is to determine the best type and dosage of probiotics for fermenting restaurant waste (FRWM) and evaluate their impact on common carp (Cyprinus carpio) fry growth. Three commercial probiotics (P1, P2, and P3) were used at an 8% concentration for fermenting the waste. The best result from the fermentation trial was tested as feed containing different FRWM proportions: 0% (TA), 10% (TB), 20% (TC), 30% (TD), and 40% (TE) with 30% protein content. The trial lasted 42 days, assessing waste chemical composition before and after fermentation, growth rate, amylase and protease activity, feed conversion, survival rate, and water quality. Results showed P1 was most effective, increasing FRWM protein content by 84.25% and reducing crude fiber and fat by 15.17% and 3.94%, respectively. TE (40% FRWM) yielded the best outcomes, with fry common carp achieving a 1.05% daily growth rate and a feed conversion ratio of 0.80, indicating efficient feed utilization. TC (20% FRWM) exhibited the highest survival rate at 88.33%. The inclusion of FRWM influenced amylase activity, increasing enzyme levels and improving feed efficiency and growth rate. In conclusion, using FRWM, fermented with P1 probiotics, showed significant improvements in its composition, leading to enhanced fish growth and feed utilization. The 40% FRWM diet demonstrated the best fish growth rate and feed conversion performance. These findings support using fermented restaurant waste as sustainable and nutritious fish feed in aquaculture.

Valorization of straw biomass into lignin bio-ink, bacterial cellulose and activated nanocarbon through the trade-off alkali-catalyzed glycerol organosolv biorefinery

Integrated lignocellulosic biorefinery that transforms low-value lignocellulose into multiple value-added products is crucial for a low-carbon sustainable development. Herein, a one-pot alkali-catalyzed glycerol organosolv (ALGO) pretreatment-based integrated biorefinery process to directionally produce lignin bio-inks, bacterial celluloses (BCs), and activated nanocarbons (ANCs) was proposed. ALGO pretreatment could modify the structure of dissolved lignins by glycerolysis. The extracted lignin fragments with high-purity (>90 %), uniform with low molecular weight (2500–4000 of Mw), and abundant hydrophilic aliphatic –OH were promising candidates in 3D-printable inks preparation. The glycerolysis reaction during ALGO process also enabled pretreated substrates toward high hydrolyzability and protected pretreatment liquor from generating fermentable inhibitors, making the solid fractions more liable for enzymatic deconstruction and microbial fermentation. Without any detoxification treatments, hydrolysates from ALGO pretreated substrates were used directly as carbon sources for BCs production, resulting in the BC yields were 56 % higher than that of the commercial glucose. The enzymatic hydrolysis residue and BC fermentation waste liquid were synthesized into ANCs via a facile carbonization process, which could further increase the value of ALGO biorefinery. Calculations showed that this ALGO integrated strategy rendered the conversion of ∼75 % lignins in pretreatment liquor to bio-inks and nearly 100 % solid fractions to BCs and ANCs. Unlike the conventional “lignin-first” route to obtain high-purity cellulose by sacrificing the value-adding conversion ability of by-products, the designed technical route in this work achieved a good trade-off between fractionation ability and subsequent conversion potential, inspiring further exploration of the technical correlation between biomass fractionation and bioproduct processing.

Optimization of Clostridium beijerinckii semi-solid fermentation of rape straw to produce butyric acid by genome analysis

Butyric acid is a volatile saturated monocarboxylic acid, which is widely used in the chemical, food, pharmaceutical, energy, and animal feed industries. This study focuses on producing butyric acid from pre-treated rape straw using simultaneous enzymatic hydrolysis semi-solid fermentation (SEHSF). Clostridium beijerinckii BRM001 screened from pit mud of Chinese nongxiangxing baijiu was used. The genome of C. beijerinckii BRM001 was sequenced and annotated. Using rape straw as the sole carbon source, fermentation optimization was carried out based on the genomic analysis of BRM001. The optimized butyric acid yield was as high as 13.86 ± 0.77 g/L, which was 2.1 times higher than that of the initial screening. Furthermore, under optimal conditions, non-sterile SEHSF was carried out, and the yield of butyric acid was 13.42 ± 0.83 g/L in a 2.5-L fermentor. This study provides a new approach for butyric acid production which eliminates the need for detoxification of straw hydrolysate and makes full use of the value of fermentation waste residue without secondary pollution, making the whole process greener and more economical, which has a certain industrial potential.Graphical

Soluble carbon source recovery using preconditioning coagulants for applicable short-term fermentation of waste activated sludge in WWTPs

A huge production of waste activated sludge (WAS) has been a burden for wastewater treatment plants (WWTPs) with high disposal cost and little benefit back to wastewater purification. The short-chain fatty acids (SCFAs) produced by a short-term acidogenic fermentation of WAS before methane production have been proven to be a high-quality carbon source available for microbial denitrification process. The dual purpose of full recovery of fermentation liquid products and facilitating disposal of residual solid waste necessitate an efficient solid-liquid separation process of short-term fermentation liquid. The transformation and loss of various soluble carbon sources between solid and liquid are very important issues for carbon recovery efficiency when combining short-term fermentation and sludge dewatering in WWTPs. Here we testified the three conventional preconditioning coagulants, Polyferric Sulfate (PFS), Poly Aluminum Chloride (PAC) and Polyacrylamide (PAM), to improve the efficiency of subsequent solid-liquid separation. The results show that conversion yield of SCFAs in the liquid phase of sludge after short-term fermentation was 195 mg COD/g VSS, when using the coagulants PFS, PAC, and PAM for recovery, the recovery ratio was 79.5%, 82.0%, and 85.9%, respectively, while the dewaterability could be improved after preconditioning short-term fermentation sludge. The complexation of Al3+/Fe3+ in metal coagulants with carboxyl groups of SCFA demonstrated by Density Functional Theory calculation led to small part of soluble carbons co-migration to the solid phase, mainly a loss of high molecular weight organic compounds (carbohydrate, proteins, humic acids), while the application of PAM had little impact on carbon recovery. Economic calculations further showed PAM preconditioning short-term fermentation liquid of WAS could achieve higher recovery benefits.

Corrosion Assessment of Metals in the Presence of Food Waste Fermentation Solution Through the Experimental Study

This paper describes an experimental study on the corrosion assessment of metals in the food waste fermentation solution. The corrosive degree of metals under different submersion conditions is assessed through the weight loss method. The experimental results indicate that HT200, Q345B, and 45 steel are rapidly corroded (weight loss values over 80, 221 mg/m2 after 192 hours). Although 304 shows a better corrosion-resistant ability, it is slightly corroded (weight loss: 1, 782 mg/m2 after 192 hours) under the interval submersion condition. The food waste treatment facilities, especially pipelines, and bioreactors should avoid iron-based materials.

The Effect of Polyglutamic Acid Produced from Glutamic Acid Wastewater on Maize Growth

This experiment uses polyglutamic acid water-soluble fertilizer produced from glutamic acid fermentation waste liquid as the experimental fertilizer to study its impact on maize yield and quality in maize cultivation. The results showed that compared to farmers who are accustomed to fertilization, the application of the new water-soluble polyglutamic acid fertilizer reduced the bald head length of corn by 0.7 cm; The weight of 100 grains of corn increased by 0.7g, resulting in an increase of 26.7 kilograms of corn per mu, with a yield increase of 5%.

Revalorization of beer brewing waste as an antifungal ingredient for bread biopreservation

This study assesses the potential revalorization of beer bagasse (BB), an important food industry waste, as antifungal ingredient in bread, by lactic acid bacterial (LAB) fermentation of this food waste. Initially, in vitro studies of the metabolite and antifungal activity were performed for the preparation of a microbial culture medium for the LAB. The culture medium with a 20% BB was determined as the optimal for the bacterial growth. Therefore, bread was prepared with a 5% and 10% (w/w) of a dried powder of this fermented culture medium as ingredient. The fermentation and heat treatment during baking did not compromise the antifungal metabolites in the bread. In the trials of the augment of the shelf-life the bread with a 10% concentration of the ingredient extended the shelf life of the bread by a 1 day and 3 days against Aspergillus flavus and Penicillium commune, respectively, compared to a regular bred. When studying the mycotoxin production in the bread the addition of the ingredient at a 10% concentration resulted in an 86% reduction in aflatoxin concentration compared to the control bread. Moreover, this ingredient did not importantly deteriorate the technological parameters of the bread.

Enhanced Food Waste Chain Elongation for Caproate Production: Role of Inorganic Carbon and Optimization Strategies

In this study, the role of inorganic carbon in chain elongation fermentation was investigated by examining its effects at different carbonate concentrations. The results demonstrated that higher yield of caproate (6.3±0.3 g/L - 7.4±0.2 g/L) was achieved with a NaHCO3 concentration of 2.5-5.0 g/L. Building upon these findings, a chain elongation process for food waste was developed. The caproate productions of control, CO2 and Na2CO3 trials were 4.6±0.2 g/L, 7.3±0.1 g/L, and 8.3±0.2 g/L, respectively. Chain elongation fermentation of food waste (1t TS) with Na2CO3 enhancement could synthesize 116.9 kg of caproate and 72.5 kg of carbon could be converted in caproate, accounting for 15.5% of the total organic carbon in the food waste. This study provided a comprehensive exploration of the chain elongation process for food waste, offering insights for further optimization and enhancement of food waste chain elongation performance coupling inorganic carbon utilization.

Fermentation of waste water from agar processing with Bacillus subtilis by metabolomic analysis.

Fungal infection has become a major threat to crop loss and affects food safety. The waste water from agar processing industries extraction has a number of active substances, which could be further transformed by microorganisms to synthesize antifungal active substances. In this study, Bacillus subtilis was used to ferment the waste water from agar processing industries extraction to analyze the antifungal activity of the fermentation broth on Alternaria alternata and Alternaria spp. Results showed that 25% of the fermentation broth was the most effective in inhibited A. alternata and Alternaria spp., with fungal inhibition rates of 99.9% and 96.1%, respectively, and a minimum inhibitory concentration (MIC) was 0.156μg/mL. Metabolomic analysis showed that flavonoid polyphenols such as coniferyl aldehyde, glycycoumarin, glycitin, and procyanidin A1 may enhance the inhibitory activity against the two pathogenic fungal strains. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that polyphenols involved in the biosynthesis pathways of isoflavonoid and phenylpropanoid were upregulated after fermentation. The laser confocal microscopy analyses and cell conductivity showed that the cytoplasm of fungi treated with fermentation broth was destroyed. This study provides a research basis for the development of new natural antifungal agents and rational use of seaweed agar waste. KEY POINTS: • Bacillus subtilis fermented waste water has antifungal activity • Bacillus subtilis could transform active substances in waste water • Waste water is a potential raw material for producing antifungal agents.

Regulation of hydraulic retention time on caproic acid production via two-phase anaerobic fermentation of Chinese cabbage waste with autopoietic electron donors

The effects of hydraulic retention time (HRT) on the performance of two-phase anaerobic fermentation for caproic acid production from Chinese cabbage waste (CCW) were investigated. In the electron donor phase, yeast was inoculated to achieve efficient autopoietic ethanol, providing electron donors for the chain elongation process. Shorter HRT led to drastic fluctuations in microorganisms, thus resulting in lower acid yields at HRT of 6 days. At HRT of 10 days, the balanced collaboration of various key bacteria avoided the accumulation of intermediate by-products, and the caproic acid production reached 4660 mg COD/L, which was 119.5% and 154.8% higher than that at HRTs of 6 and 14 days, respectively. At HRT of 14 days, the low ethanol loading rate resulted in ethanol excessive-oxidation to acetic acid. Acetic acid accounted for 41.5% of the total product, while the selectivity of caproic acid was only 15.3%. The main contributor to the production process of caproic acid was Caproiciproducens, while the Ruminalococcaceae also played a role in the process. This study provided a theoretical basis for the efficient production of caproic acid through continuous fermentation with autopoietic electron donors.

Mathematical Model of Biomethane Yield at Anaerobic Methane Fermentation of Organic Wastes: Influence of Various Parameters and Factors

Mathematical Model of Biomethane Yield at Anaerobic Methane Fermentation of Organic Wastes: Influence of Various Parameters and Factors

Modeling of biotechnological objects

The article discusses the system of modeling biotechnological objects and biogas production in the process of fermentation of various agricultural wastes. The complexity of automation of biotechnological processes, which consists in the lack of sufficient knowledge about the phenomena associated with the process of fermentation and the synthesis of target materials, is shown. Solutions to control problems using intelligent methods, intelligent control systems, based on fuzzy logic and on the basis of on the basis of neural network technologies, which have proven themselves in the control of complex objects with parameters that vary widely, as well as the analysis of algorithms for the operation of programmable logic controllers that perform the functions of regulators in the systems of operational control of complex processes, adaptive neuro-fuzzy architecture. Distributed in management decision support systems, it is made in the form of a six-layer neural structure, i.e. systems with neuro-fuzzy regulators, are able to largely meet the modern requirements of the designed systems, as a result of which the systems, using the technology of synthesis of intelligent control algorithms, can optimize complex circuits of automatic control systems.

QUALITY OF ECO ENZYME PRODUCED THROUGH A FERMENTATION PROCESS IN VARIOUS "TEMPE" YEAST CONCENTRATIONS

Organic waste that accumulates and is not adequately managed causes disease and environmental problems. Therefore, one method to solve the problems is to convert it into eco enzyme, a liquid created from the fermentation of organic waste, specifically vegetable and fruit peels, sugar, and water. Anaerobic fermentation is utilized to produce eco enzymes, with yeast added to shorten the fermentation time. The goal of this research is to determine the effect of "tempe" yeast concentration on the quality of eco enzymes. Eco enzyme was made from brown sugar, fruit peels (oranges and melons), and water in a 1:3:10 ratio. "Tempe" yeast concentrations of 1, 2, 3, 4, and 5 %w/v were used in the fermentation process for producing eco enzyme. The eco enzyme products were examined by analyzing pH value, acetic acid content, Total Dissolved Solids (TDS) value, organoleptic properties (aroma and color), and protease enzyme activity. The pH and TDS values of eco enzyme products increased as the concentration of "tempe" yeast increased. The results showed that eco enzyme products have pH values in the range of 3.5-4, acetic acid content of 0.81-1.08 %v/v, TDS value of 1000-2000 ppm, with fermented and orange aroma and a bright yellow color. According to the results, the addition of 3 %w/v "tempe" yeast in the production of eco enzyme was selected as a sample tested for protease enzyme activity and a clear zone was identified around the colony, indicating that there was protease enzyme activity.

The potential of local orange peel-derived eco-enzymes in producing indole acetic acid

Background: Ecoenzymes, created from the fermentation of organic citrus waste, offer a sustainable method to produce Indole Acetic Acid (IAA), a phytohormone vital for plant growth. This study investigates the potential of these ecoenzymes in promoting sustainable agriculture. Objective: This study aims to evaluate the capacity of ecoenzymes derived from local citrus organic waste to synthesize IAA hormones. Methods: The ecoenzyme was extracted from fruit powders and centrifuged to separate the supernatant. One ml of ecoenzyme supernatant was then mixed with 2 ml of Salkowski reagent and incubated for 12 hours at room temperature in the dark to facilitate reaction. The presence and concentration of IAA were determined using spectrophotometry at a wavelength of 530 nm, while total protein levels were measured using the Warburg-Christian method. Results: ecoenzymes from local citrus sources contain IAA, with the highest concentration observed in sample 7A (30.26 µg/ml). The ecoenzyme exhibited favorable characteristics, including an average degree of acidity of 3.55, and the highest total protein content was found in sample 2A (144.277 mg/mL). Conclusion: Ecoenzymes from local orange peels successfully produce IAA, supported by fermentation-induced microbial activity and acidic conditions. This highlights their potential in sustainable agriculture.